The spongy bone tissue in the metaphysis of the femur includes a complicated structure of bone trabeculae via which the parts of the bone subjected to compression loads and tensile loads at the femoral neck, the greater trochanter, the lesser trochanter and the diaphysis are connected in a manner transmitting compression and tension. In their totality, they form continuous tension and compression trajectories (Farbatlanten der Medizin [Colour Atlas of Medicine], Volume 7: Locomotor apparatus I., published by Thieme Verlag, Stuttgart, 1992). When the shaft of a hip-joint prosthesis is inserted, the primary tension trajectories in particular, which connect the femoral neck to the opposite intertrochanteric surface area of the bone, are for the most part interrupted. When they subsequently are no longer involved in the transmission of forces, they regress. This applies in particular when using prostheses whose prosthesis shaft is clamped in the diaphysis and in which the proximal, metaphyseal area of the femur, especially in its lateral part, is barely involved in force transmission. Attempts have been made, using what are called tension anchors, to connect the prosthesis shaft to the area of the greater trochanter and in this way to involve the latter in the flow of forces. A rod connected to the prosthesis shaft was guided through the greater trochanter and provided on the outside with a locking nut so that, upon loading of the hip prosthesis, a tension is exerted on the greater trochanter (U.S. Pat. No. 3,995,323, EP-B-93230, DE-B-1943598). However, it has been found that, because of the constant alternating loading, mechanical tension anchors of this kind quickly come loose and therefore are effective only for a short time. It is also known to design the shaft, or a wing projecting laterally therefrom into the area of the greater trochanter, in such a way that an intimate connection is obtained with the bone substance growing into pores or openings of this wing (GB-A-1030145, FR-A-2356465, EP-A-128036, EP-A-222236, EP-A-95440, EP-B-601223, EP-A-1044665, U.S. Pat. Nos. 5,755,811, 4,718,915, 5,370,698, FR-C-2194123). To promote connection of the bone to the prosthesis surface, it is also known to make the prosthesis surface osteoconductive. This term denotes surfaces which tolerate adjacent bone growth. These include surfaces made of titanium alloys and coatings which contain calcium phosphate or hydroxyapatite (EP-A-761182, WO 9308771).
More recently, substances have been made known which not only tolerate bone growth like the osteoconductive surfaces, but stimulate undifferentiated pluripotent stem cells for conversion to bone cells (Albrechtsson, Johansson: Osteoinduction, Osteoconduction and Osseointegration, in: Gunzburg Press: The use of bone substitutes in spine surgery; Springer. Denissen, H. et al.: Ceramic hydroxyapatite implants for the release of bisphosphonate, in: Bone and Mineral 1994, pages 123-134. Yoshinari, M. et al.: Bone response to calcium phosphate-coated and bisphosphonate-immobilized titanium implants, in: Biomaterials 2002, pages 2879-2885. Yoshinari, M. et al.: Immobilization of bisphosphonates on surface-modified titanium, in: Biomaterials 2001, pages 709-715). These substances include bisphosphonates and bone morphogenic proteins (BMP). These can also be used to finish the surfaces of bone prostheses, including hip prostheses (US-A-2002/0049497, US-A-2002/0127261). They lead to a very intimate connection of the prosthesis surface with the bone, which may be undesirable in the event of follow-up surgery because removal of the prosthesis from the bone may be impeded by this. This applies in particular when the shaft of a hip prosthesis is equipped in its entirety or to a substantial extent with such a substance (EP-A-478532, U.S. Pat. No. 6,296,667, DE-A-19508753).